261239904 has 60 divisors (see below), whose sum is σ = 768306924. Its totient is φ = 87079104.

The previous prime is 261239899. The next prime is 261239929. The reversal of 261239904 is 409932162.

261239904 is a `hidden beast` number, since 2 + 612 + 39 + 9 + 0 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 47802 + ... + 52985.

Almost surely, 2^261239904 is an apocalyptic number.

261239904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

261239904 is an abundant number, since it is smaller than the sum of its proper divisors (507067020).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261239904 is a wasteful number, since it uses less digits than its factorization.

261239904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100809 (or 100792 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 261239904 is about 16162.9175584113. The cubic root of 261239904 is about 639.2633973302.

The spelling of 261239904 in words is "two hundred sixty-one million, two hundred thirty-nine thousand, nine hundred four".